GTA
General Discussion To Gateway To Airguns => The Shop => : mthomas September 27, 2009, 03:11:42 AM
-
What tool do you use to hone the compression chamber?
I could use some advice on what some of you guys use to perform this step. Also, I know it should not be polished, but what is the correct finish? What rookie mistakes should be avoided? With regards to seal fitting, do you dress them to fine tune the fit , or get one that is close and let it wear in?
Thanks in advance.
-
mthomas, I use a brake hone tool a got from the local auto parts store. I had to purchase a drill bit extention for it though. As for honing, this was my method,...which I'll probably get 'horse-laughed' at. I insert the hone and lightly snug the tension adjustment on it to where I can still turn the BH by hand. The way I see it, you just want to knock off any irregularities inside the comp tube. Next I run some warm soapy water into the tube and honed the comp chamber with a cordless drill at low speed. I don't think it takes too much honing to get the desired results,...but so far this method has worked for me. Just becareful that the honing contacts don't come too close to the slotted area, or they might catch and mar the inside of the tube in this area. Maybe Gene or Bob will offer their advise with a more detail method and correct me if I'm wrong. Good Luck, tjk
-
I basicly do the same thing but mark how far I can pull out the hone with out getting into the slots with a piece of tape on the hone shaft, also I use wd 40 as a lube when honeing , howie
-
It's a good idea to use a three point hone as it is self centering and cuts more evenly. The stones should be preferrably 200-220 or at the most, 400- grit. Anything more is to fine and will not allow the lubrication needed for combustion. Also, using WD40 (or any petroleum solevent) is really not the best thing to use when honing as Gene learned a long time ago. The best thing to use is just plain old soapy water.
-
I don't see why using wd 40 as a lube for honing since after you are done with the honing part of the tune you clean the chamber completely since you wouldn't want either any cutting oil or grit from honing left. howie
-
I don't think any pro tuner uses anything but soap and water but I could be wrong. Among other reasons, the most important is that it (and most solvents) impregnates the metal pores. This is especially true on softer metals. That can and quite often does create a problem as Gene learned.
You cannot clean it out unless it is steamed or cleaned vigorously with soap and boiling water. Even though I did not understand it (or believe it at the time), some of the old timers way back when told me that it was a poor substance to use. It took a little while but I later understood why.
I never mentioned it to Gene during the time that he worked under me as we always used soap and water. Later, on his own, he started using solvent, discovered/encountered something and wondered why. Now he uses nothing but soap and water.
My mentors were right and after tuning a few thousand guns, I haven't found anything better. That said, you can use anything that you want to use.... makes no difference to me... but your gun knows the difference.
-
Coool!!! I wasn't too far out of the ball park. Guess I rememberred a few things from watching CDT,....Thanks Bob. But let's take it a step further. I was afraid that using a high speed setting would over bore the cylinder. So I thought it best to use a slow and controlled 'up and down' motion with the hone,...but how do you find the best tension setting of the stones?!?! Like I stated earlier,.. I just set them where I could still turn the hone by hand,...then chucked it in the drill and went to work. Is it neccesary to get a bright raw metal finish in the comp area of the tube,...or just enough to smooth the 'coating' (??!?) inside the tube?!? I'm glad someone started this post because I think it's a make or break portion of any successful tune, and knowing just the correct proceedure would be very important to any amatuer home tuner and shooter that wants to bring out the best in their weapon!!!! Thanks for the input Bob!! tjk
-
Thanks so much for the information. It is really great when people with knowledge and experience are willing to share.
-
Well I just had to chime in on this one.. :) Bob is absolutely correct. When I first built my shop I had no water source or fresh water. So I bought a nice solvent tank. It was much easier to clean all the parts in solvent for me and then use the running solvent in the action while I was using the hone to cross hatch with. Like Bob said that was one thing he never told me about was why he used the sink in his shop with soap and water for the final cross hatch hone on the chambers.
Well I found out right away that using solvents for honing the action was not the way to go..:) Even after cleaning the action very well with a dry rag and stick along with compressed air to get rid of the solvent I would get after assembly of gun on the first few shots a loud pop with using Gamo 7.9 gn pellets. I was concerned at first and then consulted with Bob and finally got the scoop on how the solvents will embed themselves in the cracks and microscopic pores within the action. So then I emptied out my solvent tank and filled it with soapy water. I use a large plastic cup with real soapy water to dip my hone in like Bob did, then going through the process of honing the action.
This took care of theproblem I had with the combustion I was getting when I was post testing the guns.
I also must mention that by using the soap and water solution it makes for a much nicer cross hatch. And I must add that there is a technique to the process of honing a chamber. Hint... Not all metals are equal..:)
Just my two cents..:)
-
I would suggest a lower to medium speed for honing and the tension should not be heavy. It's best to just break the old surface and when after crosshatching you should be able to see it in the tube using good lighting. It really a matter of time and experience that you can tell when enough is enough. All guns and the metal used in them is a bit different.
-
The only thing with honing with tools/drills from a home hardware
store is they just can't spin slow enough to get a true 32* cross hatch..
Or stroke fast enough for the correct spin/stroke ratio...
I,m a bit lucky...At work we have a lathe "Tos sn55" set up for reconing
hyd / pnumatic rams....It has trench reversers..so yer can set the caridge to stroke
back and fowards....I put the tube in the chuck on 28 rpm set the trench
stops & travel speed with stones in the tool tower ...
A perfect 32* hatch...instead of spiral scratchs around the tube yer tend
to get with hardware store tools...
Pete
-
What exactly is cross hatch?
-
This image was taken from this link: http://www.jockeyjournal.com/forum/showthread.php?t=36280
(http://i646.photobucket.com/albums/uu182/speedturtle810/crosshatchpattern.jpg) (http://s646.photobucket.com/albums/uu182/speedturtle810/?action=view¤t=crosshatchpattern.jpg)
A Sunnen AN hone tool was used to properly set the I.D. of the cylinder to make it really concentric on the bore. A flex honing tool was used on the latter stage to produce this cross hatch pattern.
Here is another fine example of a cross hatch pattern:
(http://i646.photobucket.com/albums/uu182/speedturtle810/0908sunnen-crosshatch.jpg) (http://s646.photobucket.com/albums/uu182/speedturtle810/?action=view¤t=0908sunnen-crosshatch.jpg)
This image was taken from this link: http://www.productionmachining.com/articles/when-the-bore-needs-more.aspx
Hope this helps.
Speedturtle
-
Very much so...thanks speedturtle